let vm = new Vue({
    el: '#app',
    data:{
        firstname: 'Jean',
        lastname: 'DelaTour'
    },
    computed: {
        fullname: {
            get: function () {
                return this.firstname + ' ' + this.lastname;

            },
            set: function (value) {
                console.log(value);
                let parts = value.split(' ');
                this.firstname = parts[0];
                this.lastname = parts[1];

            }
        },
        foo: function () {
            console.log('foo called')

        }
    }

});